scholarly journals AN ELECTRON MIRROR AS AN OBJECTIVE LENS OF THE TRANSMISSION ELECTRON MICROSCOPE

2021 ◽  
Vol 27 (S1) ◽  
pp. 1600-1601
Author(s):  
Seitkerim Bimurzaev ◽  
Yevgeniy Yakushev
Author(s):  
H. Tochigi ◽  
H. Uchida ◽  
S. Shirai ◽  
K. Akashi ◽  
D. J. Evins ◽  
...  

A New High Excitation Objective Lens (Second-Zone Objective Lens) was discussed at Twenty-Sixth Annual EMSA Meeting. A new commercially available Transmission Electron Microscope incorporating this new lens has been completed.Major advantages of the new instrument allow an extremely small beam to be produced on the specimen plane which minimizes specimen beam damages, reduces contamination and drift.


Author(s):  
M. G. R. Thomson

The variation of contrast and signal to noise ratio with change in detector solid angle in the high resolution scanning transmission electron microscope was discussed in an earlier paper. In that paper the conclusions were that the most favourable conditions for the imaging of isolated single heavy atoms were, using the notation in figure 1, either bright field phase contrast with β0⋍0.5 α0, or dark field with an annular detector subtending an angle between ao and effectively π/2.The microscope is represented simply by the model illustrated in figure 1, and the objective lens is characterised by its coefficient of spherical aberration Cs. All the results for the Scanning Transmission Electron Microscope (STEM) may with care be applied to the Conventional Electron Microscope (CEM). The object atom is represented as detailed in reference 2, except that ϕ(θ) is taken to be the constant ϕ(0) to simplify the integration. This is reasonable for θ ≤ 0.1 θ0, where 60 is the screening angle.


The theory of deconvolving the microdiffraction data-set available in a scanning transmission electron microscope or, equivalently, the set of all bright- and dark-field images available in a conventional transmission electron microscope to obtain super- resolution micrographs (which are not limited by the transfer function of the objective lens) is developed and described with reference to holography and other phase-retrieval schemes. By the use of a Wigner distribution, influences of the instrument function can be entirely separated from the information pertaining to the specimen. The final solution yields an unambiguous estimate of the complex value of the specimen function at a resolution which in theory is only limited by the electron wavelength. The faithfulness of the image processing is shown to be not seriously affected by specimen thickness or partial coherence in the illuminating beam. The inversion procedure is remarkably noise insensitive, implying that it should result in a robust and practicable experimental technique, though one that will require very large computing facilities.


Author(s):  
J. W. Wiggins ◽  
M. Beer ◽  
D. C. Woodruff ◽  
J. A. Zubin

A high resolution scanning transmission electron microscope has been constructed and is operating. The initial task of this instrument is to attempt the sequencing of DNA by heavy-atom specific staining. It is also suitable for many other biological investigations requiring high resolution, low contamination and minimum radiation damage.The basic optical parameters are: 20 to 100 KV acceleration potential, objective lens focal length of 1.0 mm. with Cs = 0.7 mm., and two additional lenses designated as condensor and diffraction lenses. The purpose of the condensor lens is to provide a parallel beam incident to the objective, and the diffraction lens produces an image of the back focal plane of the objective in the plane of an annular detector.


2000 ◽  
Vol 6 (S2) ◽  
pp. 178-179
Author(s):  
K. Kaji Ueda ◽  
T. Aoyama ◽  
S. Taya ◽  
H. Tanaka ◽  
S. Isakozawa

The ability to obtain elemental maps in a transmission electron microscope (TEM) or scanning transmission electron microscope (STEM) is extremely useful in the analysis of materials, and semiconductor devices such as ULSI's and GMR heads. Hitachi has developed a new type of elemental mapping system, consisting of a STEM (Hitachi, HD-2000) equipped with a two-window electron energy filter. In-situ calculation of the energy-filtered signal makes it possible to observe real time elemental mapping images with nanometer resolution.Figure 1 shows a schematic of the elemental mapping system. In the STEM, electrons are generated from a cold field emission gun and accelerated to a potential of 200 kV. The electrons arc focused by the objective lens into a small probe (<1 nm), which is then rastered over the specimen using scanning coils. Transmitted electrons are collected by an energy filter, which is located beneath the specimen., and consists of quadrupole lenses, a magnetic prism spectrometer and two kinds of electron beam energy detectors.


Author(s):  
D.K. Dewald ◽  
T.C. Lee ◽  
J.A. Eades ◽  
I.M. Robertson ◽  
H.K. Bimbaum

The ability to observe directly and at high spatial resolution the interactions between environments and materials affords the material scientist new and unique opportunities. This capability is realized in the Environmental Cell Transmission Electron Microscope Facility which has been installed as part of the Center for Microanalysis of Materials at the Materials Research Laboratory of the University of Illinois at Urbana-Champaign.The Facility is based on a JEOL 4000EX equipped with a specially designed pole piece. An aperture limited, differentially pumped, environmental cell has been installed in this pole piece. The system is shown schematically in Figures 1 and 2. Figure 1 is a plan view of a section through the objective lens pole-piece, with the microscope axis perpendicular to the plane of the paper, showing the cell enclosing the sample rod, the gas handling system and the location of the magnetically levitated Turbo-Molecular pumps. Figure 2 shows a cross-sectional view of the environmental cell and the gas handling system. As shown in Figure 2 the electron beam passes through a series of five apertures which allow the column vacuum to be maintained while the cell pressure is increased. The actual cell apertures are located at the apex of cones to minimize the gas path length, allow maximum tilt and still permit high- angle diffraction data to be obtained. Differential pumping of the cell is achieved by the four turbo- molecular pumps, the location of which can be seen in the Figures. With this arrangement the environmental cell is capable of supporting 400 torr of N2 gas which has no noticeable effect on the microscope operation. This allows the microscope to be operated with a LaB6 filament. The gas handling system was designed to handle a variety of environments including corrosive ones.


1983 ◽  
Vol 31 ◽  
Author(s):  
Shigeto Isakozawa ◽  
Isao Matsui ◽  
Shoji Kamimura ◽  
Akira Tonomura

The 200 kV electron microscope has been extensively utilized as a high grade model for diversified applications. This paper reports image resolution available at present with the Hitachi 200 kV Electron Microscope Model H-800 and possible techniques for improving present resolution limit which depends on the aberrations of objective lens.


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